On 15 January, a violent volcanic eruption occurred near the South Pacific island nation of Tongahun Aha Apayee. This could be one of the world's strongest volcanic eruptions since Pinatobo, Philippines, in 1991.
The children had a lot of curiosity about this eruption:
1. Will the eruption of the volcano affect China?
2. Can seawater extinguish volcanoes?
3. Will this summer get cold from a volcanic eruption?
……
To this end, we specially invited Ji Jianqing, a professor at the School of Earth and Space Sciences of Peking University and a volcano expert, to talk to the children about the reasons behind the incident and the impact.
Ji Jianqing is a professor at the School of Earth and Space Sciences at Peking University
Professor Ji Jianqing will be a guest in the "One Mustard" audio program "Mustard Shao" under Sanwu Hoe in the next year. Pay attention to the "One Mustard" public account, explore the various careers with your children, and listen to more career enlightenment stories.
■ Special host of Three-Five Hoe Qiu He ■ Professor Ji Jianqing
According to foreign media, there is an undersea volcano in Tonga, and a major eruption occurred on January 15, where is Tonga on the earth?
Tonga is located in the southern hemisphere of the Earth, the southern half of the Pacific Ocean, and near the Tropic of Cancer.
The eruption has attracted global media attention and is said to be the strongest volcanic eruption in nearly 30 years. Why? Why is it so influential?
Summarized from the current observational data and historical data, the Tonga volcano is indeed the strongest volcanic eruption event on the earth in recent years. There are volcanic eruptions on the earth all the time, but most of them are under the seabed, people can't see, people can see mainly volcanoes on land or volcanoes near the surface of the Earth, the surface of the sea.
Since the 19th century, the intensity of volcanic eruptions has been sorted, from Chinese meteorological enthusiasts
The eruption of The Tonga volcano can attract so much attention, mainly because it is obvious that this eruption formed a very large volcanic eruption column that shook the world, and was clearly photographed by satellites of the United States, Japan, and China - an image that fully shows the formation process of the eruption column, which is the first time for mankind. There is also a volcanic eruption column formation process accompanied by an earthquake of about 6 on the Richter scale, a relatively strong tsunami wave is formed on the surface of the seawater, and a pressure shock wave is formed in the atmosphere, so the formation of this volcanic eruption column is very spectacular and moving, which arouses the public's interest and detonates the entire media at once.
After the eruption, in addition to adults, in fact, children are also very concerned, they have a lot of questions in their little brains to ask, such as the eruption of the Tonga volcano, will it affect our China?
The location of the Tonga volcanic eruption is more than 10,000 kilometers away from China, so it is relatively far away, and it is in the southern hemisphere. I also mentioned that the eruption of the Earth's volcano is actually going on all the time, but the impact of the eruption of the Tonga volcano, which we assess from a professional point of view, is relatively small. As you may know, the Chinese earthquake department was able to detect seismic waves and tsunami waves during the volcanic eruption in Tonga a few days ago. The shock wave of air pressure has also been measured, and after it has passed through 10,000 kilometers, it has become very weak in China. In the Tonga region, there are tsunami waves of more than three meters, but in China, because of the obstruction of the first island chain, the highest is only more than 20 centimeters. Therefore, the impact is relatively small, which is reassuring to everyone.
Tonga's location on the map, from the internet
Children also want to know, this volcanic eruption can be predicted?
If it is a close-range volcanic eruption, volcano researchers can observe some signs before the eruption of the volcano and can predict it. But volcanic eruptions like the formation of giant eruptive columns like the Tonga volcano, like earthquakes, cannot be accurately predicted, which is also a very important hot issue in scientific research now.
Animation of the clouds at the moment of the eruption of the Tonga volcano, from weathermodels
If someone happens to be traveling near a volcanic eruption point, how can they escape?
Many Chinese also travel internationally and travel to many beautiful volcanic areas. If you encounter something like a volcanic eruption during your trip, like the Tonga eruption, which is a very large eruption column, it would certainly be a tragedy if it was covered by a volcanic column or captured by a lava flow at the time of the eruption.
If there is no such tragedy happening, such as a little farther away from it, thirty-six plans, escape is the best policy.
If you go a little farther and can see the eruption column, you may also be affected by the eruption. At this time, you should not expose yourself to volcanic ash or volcanic gas-filled air, and wrap your facial features, especially your mouth and nose, with a wet towel or cloth to prevent volcanic ash from causing damage to the respiratory system. There are many acidic substances in volcanic gases, such as sulfur dioxide, which will combine with water to form acid rain, which will also cause damage to the skin and body, so it is necessary to hide in some places that can avoid rain to ensure safety. Also, if you're in the middle of the ocean, or near a mountain eruption, be aware of tsunamis and landslides. If you travel to volcanic areas, or work or live, you should prepare some clean water, food, breathing masks, protective clothing and other equipment.
Are there any active volcanoes in China at present?
On the international map of the distribution of active volcanoes, we can see that the world's main active volcanoes are in the Pacific Rim, which is near the coast around the Pacific Ocean, which is the world's largest seismic volcanic activity zone. Every year, there are many volcanic eruptions and seismic activities, as well as some disasters in which seawater and land interact, such as landslides, typhoons and so on. In china, it is mainly near the first island chain off the coast of China, while our China is in the inner reaches, not on this diving belt. Therefore, China is still relatively safe in terms of volcanic disasters, please rest assured.
Pacific Rim volcanic seismic belt, from the Internet
Another child asked, this volcano is an undersea volcano, that is to say, it emerges from the sea, why is it not extinguished by the sea?
This is an interesting question, most of the world's volcanoes actually erupt on the ocean floor. In the deep sea, the depth of the sea is relatively deep, such as 4000-6000 meters deep, the volcano is to gather a lot of energy, it is difficult to break through the constraints of the water, spray to the surface of the water. But the crater of the Tonga volcano is almost near sea level, some have been exposed to sea level, of course, most of its craters are below sea level, so it is actually near sea level when it erupts, and Tonga volcano is a place with relatively large volcanic energy in the Pacific Rim. Before the eruption of the volcano, the magma inside had gathered to a certain extent, and the pressure inside had reached a very, very large, and the volcanic mountain that covered it could not suppress this force, and a sudden eruption occurred. So in fact, seawater can water volcanoes, in the deep sea, many volcanoes have been watered by seawater.
I saw in the news that the crater of the incident has awakened, the eruption period can last for weeks, even years, and it is not clear whether it has reached the peak of the eruption. There are several words in this sentence that I don't quite understand. For example, what is the crater awakening? There are also eruption activity periods and peak eruptions, can you tell us more about them?
The location of the Tonga volcanic eruption is actually the volcanic cone left over after the original previous eruption, it has partly exposed above sea level, most of it is in a relatively shallow place below sea level, the last eruption is considered to be about 1000 years ago, and then in the 20th century there were four eruptions recorded, respectively, in 1912, 1988, 2009, 2014 to 2015, and this year also small eruptions several times, the scale of the eruption is relatively small, It did not cause major disasters. In volcanic research, we often call the time when an active volcano does not erupt as dormancy.
Now it suddenly erupted again, so it woke up. The awakening of the volcano takes a while to erupt, lasting or intermittently for weeks or decades, which is called the period of eruptive activity. At a certain point in time during this active period, the volcano will spew out a large amount of lava ash or volcanic gas in one fell swoop, which is the volcanic peak period. As far as I know, in the Pacific Rim Belt, if a volcano erupts from a large eruption column, it is generally already at the peak of the eruption. Usually after a big eruption event, it ends sporadically, and I jokingly call it "tiger head and tail". So the eruption of the Tonga volcano, I think it should be smaller and smaller in scale, smaller in intensity.
Volcanic eruptions on the global cloud map, from rammb
Some videos and pictures put out of the news, we will see that when the volcano erupts, there will be a large ball of things gushing out, and then forming a big cloud. This eruption is said to have reached a height of 20 kilometers, can you tell us what material erupted from the volcano? The height of the eruption is 20 kilometers, is it high in the volcanic eruption?
During the eruption, like this one in Tonga, there are many kinds of components in the eruption column: lava, lava that has not condensed into a solid, volcanic debris, particles large and small... It is also very important that we can see very clearly on the image that the ash and volcanic gases are. Volcanic ash is pyroclastic material that is similar to or finer than flour.
Volcanic gas, I'll emphasize it here. The eruption of the Tonga volcano can form such a large eruption column, and there is already a lot of pressure in the lava chamber under the ground before the eruption, and this pressure breaks through the rock formations and water surfaces above it, and then erupts, and the energy is very large. The media also said that the energy equivalent to 1,000 Hiroshima atomic bombs was indeed so large. This energy is mainly a large amount of volcanic gas gathered inside, pressed, stretched, and then suddenly erupted to form the energy release. Because of its high energy, it can erupt into the atmosphere of more than 20 kilometers, even to the stratosphere. The main erupting gases are carbon dioxide, methane, hydrogen sulfide, nitride, and of course, water vapor is also more.
The height of volcanic eruptions varies, will the impact be different?
The eruption was not high, with Mount St. Helen probably reaching about 27 kilometers in May 1980 and Mount Pinatubo in the Philippines approaching about 40 kilometers in 1991. Of course, I also saw documentation that there were about 80 kilometers of volcanic eruption columns. The volcanic eruption of Tonga is also a relatively strong volcanic eruption.
The eruption of Mount Pinatubo, from Chinese meteorologists
What is the most important question? About 10 kilometers below is called the troposphere, the air masses are airflow, mainly above and below convection or lateral convection, called as a convection process. 10 km or more into the stratosphere, the movement of the atmosphere is mainly based on horizontal movement. If the volcanic column erupts more than 10 kilometers and enters the stratosphere, it is not a column, but spreads out in the stratosphere, forming a shape like a mushroom or umbrella, spreading out to form a thick cover, covering the bottom, and the impact on the earth is relatively large. This is because after it was spread, a lot of volcanic ash, including cold room gases, we called cold room gases that can cool the earth's atmosphere, and the sulfur dioxide of cold room gases combined with water vapor to form sulfurous acid particles floating in the stratosphere. After the sun hits the stratosphere, it directly returns the energy, and the amount of solar energy that we can absorb on the ground will decrease, so that once the energy received by the sub-ground is reduced, the entire temperature will drop, forming the so-called volcanic winter. There are many cases of this in history, and the 1991 Pinatubo volcano in the Philippines was like this.
Typhoon Yunya at the time of the eruption of Mount Pinatubo, from the Typhoon Forum
Some media also call it a year without summer, that is, there is no summer. Is it possible that this time the Tonga volcano will cause such a serious impact?
Volcanic eruptions cause global cooling, this problem is actually quite complicated, it must have a favorable time and place. Our research shows that three conditions are needed for the effects of volcanic eruptions to cause global cooling. Thanks to the 1991 case of Mount Pinatubo in the Philippines, scientists and researchers have a clear understanding of the formation of the volcano in winter.
First, volcanic eruptions occur almost near the equator, near the latitudes where the Sun's radiation is strongest. The largest absolute change caused by the blocking energy of volcanic aerosols in the volcanic stratosphere is near the equator.
Second, be sure to form an eruption column. In 2018, Kilauea Volcano in the Hawaiian Islands also erupted, but it only erupted to about 9.1 kilometers and could not transport material into the stratosphere.
Third, the eruption column should last for a period of time, and the things that erupt from the volcanic cone should continue to support the eruption column, and send a continuous stream of material into the stratosphere.
Volcanic eruptions on the H8 satellite cloud map, from tropicaltidibits
According to my judgment, the Tonga eruption already has three such conditions, but it has one flaw: the volcanic column has a relatively short duration and cannot continuously transport large amounts of cold room gas sulfur dioxide into the stratosphere.
In addition, a lot of energy from the Tonga volcano eruption is carried out underwater. Underwater eruptions have a characteristic: sulfur dioxide cold and wet gas is soluble in water, so the seawater itself also dissolves part of the cold and wet gas, so that sulfur dioxide is less. The more water vapor in the eruption column, the more water vapor there is, and the greater the likelihood of turning into heavy rainfall. Heavy rains can also dissolve large amounts of volcanic eruptive gases in the water and eventually settle to the ground. The current data from satellite imagery observations also prove one thing: the amount of cooling gas that the eruption column can deliver to the stratosphere is very small. If there is no continuous large-scale, violent eruption in the back, the cooling effect is relatively weak when the material is sent into the stratosphere. Therefore, from the current information, it is unlikely, and everyone should rest assured that they should not panic.
Editor's Note:
The fate of mankind is closely linked, and it is hoped that the affected countries and regions will resume normal life as soon as possible.
It turns out that there are so many scientific principles and stories in a volcanic eruption. What disasters will be brought about by volcanic eruptions, and will they have a positive impact on the earth? The next issue continues.